1) Field of the Invention
The present invention relates to a delivery device and, in more particular, to a delivery device that employs anchoring features to stabilize an implantable device during deployment of the implantable device within a lumen.
2) Description of Related Art
Stents are devices that are inserted into body lumina such as vessels or passages to keep the lumen open and prevent closure due to a stricture, external compression, or internal obstruction. In particular, stents are commonly used to keep blood vessels open in the coronary arteries, and they are frequently inserted into the ureters to maintain drainage from the kidneys, the bile duct for pancreatic cancer or cholangiocarcinoma, or the esophagus or airways for strictures or cancer. Vascular as well as nonvascular stenting has evolved significantly; unfortunately, there remain significant limitations with respect to effectively implanting the stents into a patient's lumen.
In order to serve its desired function, the stent should be delivered precisely and oriented correctly. Improper installation can lead to tissue luminal inflammation and tissue granulation. In order to facilitate the delivery of stents, devices, such as endoscopes and catheters, have been utilized to deploy stents more precisely. Unfortunately, guidance of the stent has substantially remained a function of physician skill resulting from substantial practice. This fact has become particularly evident with the advent of radially expanding stents. The physician frequently needs to measure the length of the lesion, align a distal end of the of the delivery device, and rely on accurate deployment to ensure that the entire lesion is covered by the stent. Moreover, when deploying the stent, a physician often displaces an outer tube relative to an inner tube, where the stent is positioned between the inner and outer tube. As the stent is deployed, the stent length often decreases due to friction between the outer tube and the stent. This decrease in stent length also decreases the positional accuracy of the deployed stent. In addition, increasing the stent column strength to compensate for length shortening affects the physical properties of the stent, which may in turn adversely affect the efficacy of the stent.
Techniques have been developed to address the problem of length foreshortening of the stent during deployment. For example, U.S. Pat. No. 6,607,551 to Sullivan et al. discloses a stent delivery system with a nested stabilizer. In particular, Sullivan discloses that the stabilizer, which is positioned within the interior of a stent, includes a surface element for engaging the stent in a region corresponding to a low-column-strength segment of the stent. The surface element could be one or more radial protuberances, as shown in FIG. 3A of Sullivan. The protuberances may include rings of various cross-sections, axial lengths, or spacing between the protuberances, or may be in the form of discrete barbs, bumps, or inflatable knobs arranged in a circumferential configuration or helical pattern about the stabilizer. The protuberances are attached to the stabilizer using techniques such as bonding or are formed in the stabilizer using techniques such as grinding.
The protuberances provide increased stabilization of the stent, especially for a low-column-strength segment, prior to deploying the stent. Despite these improvements, additional innovations in stabilizing and limiting foreshortening of an implantable device to promote more accurate delivery of the implantable device are desired.
Therefore, there is a need in the industry for a delivery device that is capable of effectively and accurately positioning an implantable device within a patient's lumen. In addition, there is a need for a delivery device that is capable of stabilizing the implantable device during deployment of the implantable device.